Variable capacitor



Aug. 31, 1937. H. HuNERKoPF VARIABLE CAPACITOR Filed lay 14, 1935 lll MII

Inventor: Henry Hunerkopf, by Www/8MM His Attorney.

Patented Aug. 31, 1937 UNITED STATES PATENT OFFICE VARIABLE CAPACITOR Henry Hunerkopf, Bridgeport, Conn., assignor to General Electric Company, a corporation of New York My invention relates to variable capacitors, and particularly to a construction of variable capacitor which is especially suitable for use as a trimmer in radio apparatus. It is the object of my invention to provide a variable capacitor which is simple and sturdy in construction, efilcient and reliable in operation and inexpensive to manufacture.

My invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claim.

Referring to the drawing of which the single figure is a cross-sectional view of a preferred embodiment of my invention, I represents the base member which is cylindrical in form and may be of any suitable insulating material but preferably of a ceramic material. The enclosing rnetallic cylindrical casing 2 having the wall 3 at one end thereof, whereby it has a cup-like shape, is firmly secured at its other end to the insulating base I. The casing is shown having a slight offset at 4 making a shoulder against which the inner edge of the base I engages and has its edge 5 swaged over the outer edge of the base. The base is constructed with a central opening therethrough and before the base is secured in the casing the rivet 6 is passed through that opening and firmly secured to the base. The upper face of the head 1 of the rivet is faced off so. as to be perpendicular to the axis of the cylindrical base I in order to form a suitable surface upon which the fixed cups are to be secured, Rivet 6 is bored out or if a hollow rivet is employed it is rebored so Ythat the opening therethrough is exactly concentric with the cylindrical face of the base I.

The fixed plates of the capacitor comprise the nested cups 9 whose outer portions are cylindrical and whose end portions are firmly secured against the upper face of rivet I by means of the rivet I0. This rivet passes through rivet 6 and is shown having the outer hexagonal head Il. It is also provided with the extension I2 to .constitute a terminal for the fixed plates of the capacitor.

The movable plates of the capacitor comprise the nested cups I4 which in form are similar to the cups 9 but which are constructed to interleave with the latter cups. Cups I4 are secured together as a unit by the central rivet I5 through which is threaded the adjusting screw I6. This screw has the integral flange I1 which engages the inner face of the end wall 3 of the casing and is held resiliently thereagainst by the spring washer I8. This Washer preferably has notches I9 therein to increase its resiliency and is held 5 under tension by the cross-pin 20 passed through a hole in the screw I6. The outermost cup I4 is constructed to snugly fit the casing 3. To increase the friction between this cup and the casing the cup preferably is provided with a plurality l0 of longitudinal slots 2I whereby the portions between the slots may'rnore readily yieldably engage the casing. Within the innermost cup I4 I have shown the small cup 22 which servesY to retain any small particles which may wear off l5 the screw. Preferably the threaded portion of the screw I6 is slightly tapered at each end thereof in order to prevent jamming of the movable and fixed parts of the capacitor.

with the construction above described it will 20 be seen that as the screw I6 is turned in one direction or the other to effect adjustment of the capacitor the group of nested cups I4 will be moved longitudinally with reference to the fixed cups, since the frictional engagement between 25' the casing and the outermost cup is sufficient to prevent any rotative movement of the nested cups I4.

I have chosen the particular embodiment described above as illustrative of my invention and" 30 it will be apparent that various modifications may be made without departing from the spirit and scope of my invention which modifications I aim to cover by therappended claim. 35

What I claim as new and desire to secure by Letters Patent of the United States, isz- A variable capacitor comprising an insulating base, a cup-like casing having its open end surrounding and secured to said base, av group of fixed nested cups in the casing, a combined terminal and securing stud for said groups of cups arranged centrally of and extending through said base, a group of movable nested cups in said casing the outermost cup of which is constructed frictionally to engage the side wall of said casing, an adjusting screw having resilient means for frictionally retaining it in the end wall of the casing and threaded into said group of movable cups and-means for enclosingfthe screw to prevent detached particles from lodging between HENRY HUNERKOPF. 

